第二级时效工艺对7050铝合金厚板组织及性能的影响
Effect of Second Step Aging on Microstructure and Properties of 7050 Aluminum Alloy Thick Plate
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摘要: 研究了第二级时效工艺对7050铝合金厚板拉伸性能、断裂韧度及电导率的影响, 并采用透射电镜及扫描电镜分析其强韧化机理。结果表明: 该合金厚板在双级时效的第一级时效条件相同时, 随第二级时效温度的升高或时效时间的延长, 合金中沉淀相的尺寸和间距增大, 合金强度下降, 断裂韧度和抗应力腐蚀能力提高, 切变和穿晶韧窝混合型断裂方式中的韧窝特征愈加突出, 且时效温度对性能的影响较时间明显; 在120 ℃×4 h+165 ℃×28 h双级时效工艺下合金具有优异的综合性能。Abstract: The influence of the second step aging treatment on tensile properties, fracture toughness and electrical conductivity of 7050 aluminum alloy thick plates was investigated. Meanwhile, the strengthening-toughening mechanism was analyzed by transmission electron microscopy and scanning electron microscopy. The results show that the sizes and distance of precipitates phases increased and the strength of the alloy decreased, the fracture toughness and the stress corrosion resistance increased, the dimple character in shearing and transgranular dimple mixed fracture was more outstanding, and the effect of aging temperature on the alloy properties was more obvious than aging time with the second aging temperature or time increasing when the first step aging conditions was same. The alloy had good comprehensive properties after aging at 120 ℃ for 4 h and 165 ℃ for 28 h.
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